This invention relates to a hob cutter for cutting gears and more particularly to a hob cutter or rack cutter capable of simultaneously cutting and chamferring an involute gear. The hob cutter in accordance with the present invention is a hob or rack cutter for cutting the chamferring gears wherein a pres­sure angle α₁ and module M of a rack tooth space of a rack for cutting a first involute gear are respectively different from a nominal pressure angle α₀ and module m but offer a so-­called transfer rack tooth shape in order to provide limit va­lues to a number of teeth vs. chamfer quantity characteristic curve and to minimize a change in a chamfer quantity. Ac­cording to the present invention, it is possible to ordinarily chamfer almost all gears from gears having a small number of teeth to gears having a large number of teeth with one kind of hob cutter.

ABSTRACT

A hob cutter for cutting gears, in particular, involute gears and at the same time for chamfering them. A pressure angle α₁ and module M of a teeth profile of a rack for cutting a first involute teeth profile are different form a nominal pressure angle α₀ and a nominal module m in their values respectively, resulting in a shifted rack teeth profile, whereby a characteric curve showing a relation between a number of teeth and chamfering values has an extremal value with a variation of the chamfering values being minimal. According to the present invention, generally a single type of the hob cutter is sufficient to cut almost all gears having a wide range of the teeth number.

The ends of gear teeth are chamfered using an arcuate motion cutter having a complex cross sectional shape. In an improvement of the prior trial and error techniques, the cutter shape is made correctly the first time using an algorithm which includes determining certain s-dimensions produced on a chamfer by a set of tool dimensions; comparing these to the desired maximum, minimum and nominal chamfer widths, and; then iteratively optimizing the set of tool dimensions to minimize the differences.

Die Erfindung betrifft ein Verfahren und Werkzeug zum Bearbeiten der Zahnfußrundungen 5 von Zahnrädern. In einem Stahlring 1 gehaltene, verschleißfeste Körper, z. B. Kugeln 3 aus Hartmetall, werden mit einer Presse gegen die Zahnfußrundungen gedrückt. Dabei entstehen durch Materialverdrängung Einprägungen 5A, durch die eine Gefügeverdichtung erzielt wird. Die Festigkeit der Zahnräder wird dadurch im Bereich der bruchgefährdeten Zahnfußrundungen erheblich verbessert.

This invention provides a surface-coated cutting tool which exhibits excellent fracture resistance and wear resistance in high-speed cutting, such as high-speed gear cutting, high-speed milling, and high-speed drilling. The surface-coated cutting tool includes a hard coating layer composed of an alternately laminated layer structure of at least a thin layer A and a thin layer B formed on the surface of a tool substrate, such as a cemented carbide substrate, a cermet substrate, and a high-speed tool steel substrate. The thin layer A is an (Al, Cr, Si)N layer which satisfies a compositional formula: [AlxCrySiz]N (0.2≤X≤0.45, 0.4≤Y≤0.75, 0.01≤Z≤0.2, and X+Y+Z=1 in terms of atomic ratio). The thin layer B is an (Al, Ti, Si)N layer which satisfies a compositional formula: [AluTivSiw]N (0.05≤U≤0.75, 0.15≤V≤.94, 0.01≤W≤50.1, and U+V+W=1 in terms of atomic ratio).

Rotary shaping blades (20) for forming rack teeth (2) by cutting into rack formation surfaces (16) of pipe bodies (11) are arranged in parallel to one another in a row in the longitudinal direction of pipe bodies (11). The direction in which rotary shaping blades (20) are arranged is maintained parallel to the length of pipe bodies (11). Numerous rack teeth (2) are simultaneously formed on rack formation surfaces (16) of respective pipe bodies (11) by rotary shaping blades (20). At that time, the center of trough portion (2a) of one of rack teeth (2a) being formed on rack formation surface (16) of each pipe body (11) is cut through by rotary cutting blade (22) simultaneously with formation of rack teeth (2). Even in a state where rack teeth (2) of pipe body (11) are separated, their undulations reliably correspond to each other, and the strength of rack teeth (2) are maintained so that they are prevented from chipping.

Das Verfahren zur Bestimmung der Längs- und der Profilmodifikation der Oberfläche des Zahns (I) eines Werkzeuges, das mit dem zu bearbeitenden Zahnrad linear gekoppelt ist, besteht in der Ermittlung der Kennwerte der Modifikation nach der Beziehung:wo ö - den Wert der Modifikation der Oberfläche des Werkzeugzahns (I) in der zum Radius r der Lage des Berührungspunktes auf der bearbeitenden (5) Oberfläche senkrechten Richtung vom Drehpunkt (0) des Werkzeuges her,

△p - den erforderlichen Zuwachs der Normalkomponente der Schnittkraft,

G - die auf die Werkzeugachse bezogene Steifigkeit des Systems, welches synchrones Drehen des Werkstücks und des Werkzeuges sicherstellt, bedeutet.

Die Werkzeugmaschine zum Herstellen und Abrichten eines Werkzeuges und Fertigbearbeiten von Zahnrädern enthält drei Spindeln (4, 5, 15), die in eigenen Spindelstöcken (2, 3) bzw. einem Träger (17) gehaltert und mit Antrieben (8,11) versehen sind, wobei zwei der Spindeln (4, 5) synchron miteinander verbunden sind und die dritte Spindel (15) im Träger (17) frei drehbar und axial verschiebbar ist, welcher radial- und winkeleinstellbar ist.